A federal judge has allowed gay marriage in Utah to continue, making Utah the 18th state plus the District of Columbia where gay and lesbian couples can marry.

Judge Richard Shelby on Monday denied a request by the state that sought to halt gay marriage until the appeals process plays out.

The same judge overturned Utah's ban on same-sex marriage Friday, ruling it is unconstitutional.

Utah lawyers are expected to ask a higher court to put the process on hold.

"We're thrilled that this decision continues the process of decisions across the country that support the right of gay and lesbian couples to get married and have their love and families protected equally under the law," said Brian Silva, executive director of Marriage Equality. The New York City-based group promotes the rights of gay and lesbian couples to marry.

The state of Utah is now expected to appeal the decision to the Tenth Circuit

The county clerk in Salt Lake City immediately began issuing licenses Friday, and hundreds more gay couples were in line to be married on Monday.

The ruling drew attention given Utah's long-standing opposition to gay marriage and its position as headquarters for the Mormon church.

Lawyers for the state are waging a legal battle on several fronts as they seek to stop the same-sex weddings.

They were twice rejected by the 10th U.S. Circuit Court of Appeals.

Clerks in several counties were issuing the licenses to gay couples Monday morning, and people began lining up Sunday in Salt Lake County. Hundreds of couples were lined up at the clerk's office by the time doors opened.

"We're going to do it until the judge says stop," said Kerri Nakamura, a staff assistant for a county councilman who was helping people process licenses.

Shelby on Friday overturned the state's same-sex marriage ban, ruling that Utah's law violates gay and lesbian couples' rights under the 14th Amendment.

The decision that has put Utah in the national spotlight because of its long-standing opposition to gay marriage.

On Sunday, a federal appeals court rejected the state's emergency request to stay the ruling, saying it couldn't rule on a stay since Shelby hasn't acted on the motion before him. The court quickly rejected a second request from Utah on Monday.

Following Shelby's surprising ruling Friday afternoon, gay and lesbian couples rushed to a county clerk's office in Salt Lake City to get marriage licenses. More than 100 couples wed as others cheered them on in what became an impromptu celebration an office building about three miles from the headquarters of the Mormon church.

About 25 couples lined up outside the clerk's office in Davis County on Monday morning, the Standard-Examiner reported. The first couple showed up around 6 a.m. and married immediately after receiving their license.

For now, a state considered as one of the most conservative in the nation has joined the likes of California and New York to become the 18th state where same-sex couples can legally wed. Legal experts say that even if a judge puts a halt to the weddings, the licenses that have already been issued will likely still be valid.

Utah is home to The Church of Jesus Christ of Latter-day Saints, which was one of the leading forces behind California's short-lived ban on same-sex marriage, Proposition 8, which voters approved in 2008. The church said Friday that it stands by its support for "traditional marriage" and that it hopes a higher court validates its belief that marriage is between a man and woman.

In Shelby's 53-page ruling, he said the constitutional amendment Utah voters approved in 2004 violates gay and lesbian couples' rights to due process and equal protection under the 14th Amendment. Shelby said the state failed to show that allowing same-sex marriages would affect opposite-sex marriages in any way.

The decision drew a swift and angry reaction Republican Gov. Gary Herbert, who said he was disappointed in an "activist federal judge attempting to override the will of the people of Utah." The state quickly took steps to appeal the ruling and halt the process, setting up Monday's hearing before Shelby.

The ruling has thrust Shelby into the national spotlight. He has been on the bench for less than two years, appointed by President Barack Obama after GOP Sen. Orrin Hatch recommended him in November 2011.

Shelby served in the Utah Army National Guard from 1988 to 1996 and was a combat engineer in Operation Desert Storm. He graduated from the University of Virginia law school in 1998 and clerked for the U.S. District Judge J. Thomas Greene in Utah, then spent about 12 years in private practice before he became a judge.